I was thinking about the sh60 with multiple drivers.
I'm sure there is a crossover in the sm100 still. I doubt it's just a raw driver on a waveguide. If it is I'm surprised!
I believe PSAC had good measurements comparing some DIY cabinets including the TH-18.
I didn't have my UMIK until recently. I will get around to taking measurements when I have a day off
But I'm not so sure how to get accurate impedance measurements for you.
Btw a "coax" driver usually implies that there is another driver mounted behind it and "passes through" the coax. So the spec listed there that it is only a single driver is most likely wrong, there must be a compression driver mounted behind it. I also say that because that loudspeaker responds to 20kHz.
Unless by coaxial driver they mean a midrange 8" driver with a compression driver mounted to itself, and are calling that a single unit.
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Yes so I guess there would have to be some network. Eminence has some ok coaxial speakers 8" 10" and 12" wish I had some plans for the SM100.
The sm100 is a simple 100 deg waveguide that surrounds a 8 in coax driver with the back enclosure forming a bass reflex cabinet with 4 forward firing ports. A pretty nice inexpensive diy build can probably be obtained with the Eminence Beta 8cx and CD with a 2.5k crossover. The trick is the molded and curved waveguide. I will see if I can design something and model with Akabak. We will have to approximate the design with flat panels. An option is to use bendy plywood or curved foam core and cover with fiberglass and resin.
It's getting OT here so maybe I need to start a new thread for the SH100-inspired speaker in the Multiway forum. Here are some preliminary results with the Eminence Beta 8CX though. The box is 20.7 in (W) x 20.7 in (H) x 9.0 in (D) with qnty 4 x 2.0 in dia x 4.0 in long ports. Use 18 mm thick plywood and adjust the internal volume to 1.14 ft3. Line with walls with fiberglass. Make the horn from 4 panels starting at 7.13 in wide at the throat where the driver is backside mounted and 14.0 in at where the horn mouth exits the box. The axial depth of the 4-panel horn is 2.41 inches (you will have to figure out the cut outline using cardboard prototypes). This gives a 110 deg coverage per the specs of the SH100. The Eminence Beta 8CX is a nominal 93 dB sensitive driver and this will achieve +/-3 dB from 70 Hz to 2500 Hz in this ported config. Couple this with an appropriate crossover like the PBX2:2k5CX and a compression driver like the ASD1000. You will have to pad the CD to match the 93 dB output of the main driver. The main driver's mids are enhanced by the horn mouth and may need a 6 ohm resistor strapped in parallel with the 2 mH coil on the crossover to flatten the rising response.
Here is the freq response of the bass driver far from walls and at a height of 30 in above the floor.
Here is the polar response if we put a typical CD into the main unit. I modeled the horn using the dimensions of the Beta CX internal horn and paper cone as a secondary horn leading to the final 110 deg 4-panel horn.
It looks like it has very uniform dispersion from 100 Hz to 10 kHz. Appears to be a relatively easy box to make once you figure out the horn panel cuts. Good luck.
X
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Very cool I have seen the 10" CX is the best of the lot between the 8" 10" and 12" drivers . how different would the box be for the 10" cx driver?
For the beta 10CX, if you scale the box to 26 in x 26 in x 12 in deep, use qnty 4 x 3.0 in dia x 6.0 in long vents, make the 4 panel horn go from 9.2 in at the driver surround to 17.5 in on an edge at the mouth exit over an axial distance of 3.0 in you get this for the freq response. It is now 95 dB efficient and the bass extension goes to -3dB at 60 Hz. Any more discussion and I will post a new thread.
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Very nice of you to provide mic and impedance results for the speaker.
Here's a little cookbook method for getting impedance traces. I wont describe how to calculate/guesstimate the exact impedance but the only things usually needed are relative impedance (which reveals the extent of cone motion) and at what frequencies peaks appear.
First, the signal to your amp must be non-EQ flat.
Put an 8-ohm resistor (or anything thereabouts) across the output of your amp. You can work with small signals and so even a two-watt resistor is OK (with 8-ohms, if you keep under say, 3 vrms output from the amp... typical enough playing level anyway), but bigger is safer.
Then parallel to the 8-ohm resistor, from "hot" to "ground" terminals: a 200-ohm resistor (anything 100-500 is OK), 1/2 watt OK, then the driver.
Measure voltage across the driver, taking care to ensure computer ground is the same as amp ground. No problem working with alligator clips and unshielded wires.
Ben
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For reference. Some pics showing size difference between PAL12 and TH-18
(Only things that are slightly misleading are 1. My basement floor is uneven, 2. The casters on the TH-18 were placed slightly lower than the ground plane, so they are lifting the back of the cabinet slightly off the ground. I did this to see if caster vibration could be eliminated. I figure with enough weight from the rest of the system on top of the TH-18, "walking" will not be a problem.)
(Only things that are slightly misleading are 1. My basement floor is uneven, 2. The casters on the TH-18 were placed slightly lower than the ground plane, so they are lifting the back of the cabinet slightly off the ground. I did this to see if caster vibration could be eliminated. I figure with enough weight from the rest of the system on top of the TH-18, "walking" will not be a problem.)
have you tryed tightening the nuts on the casters?For reference. Some pics showing size difference between PAL12 and TH-18
(Only things that are slightly misleading are 1. My basement floor is uneven, 2. The casters on the TH-18 were placed slightly lower than the ground plane, so they are lifting the back of the cabinet slightly off the ground. I did this to see if caster vibration could be eliminated. I figure with enough weight from the rest of the system on top of the TH-18, "walking" will not be a problem.)
I'm using these from PE:
Penn-Elcom W8975 4" Fixed Caster w/Blue Wheel 330 lb. 262-274
They're good casters with roller bearings. No other issues and they're beefy as hell. The rattling isn't even bad at all I'm just being picky.
I have not even used these since I got them back. I tested them with a few different amps with no high pass, at low volume. No high output testing and no outdoor testing. I will get around to that once these are all finished up
Penn-Elcom W8975 4" Fixed Caster w/Blue Wheel 330 lb. 262-274
They're good casters with roller bearings. No other issues and they're beefy as hell. The rattling isn't even bad at all I'm just being picky.
I have not even used these since I got them back. I tested them with a few different amps with no high pass, at low volume. No high output testing and no outdoor testing. I will get around to that once these are all finished up
